The s6-clockadd program

s6-clockadd adjusts the system clock depending on the input
provided by a time client.

Interface

s6-taiclock server | s6-clockadd [ -f ] [ -e errmax ]

s6-clockadd reads its stdin, expecting input from a program such
s6-taiclock or
s6-sntpclock (which get time from a
time server).

It sets the system clock so the system time becomes the one
given by the server. Then it exits 0.

Options

-f : force. Normally, s6-clockadd exits 1 if the
time discrepancy read from stdin is bigger than errmax
milliseconds. If this
option is set, it will print a warning message, but still set the
system time and exit 0.

-e errmax : accept a maximum time
discrepancy of errmax milliseconds. By default, errmax
is 2000.

Notes

s6-clockadd must be run as root. The client getting the time
from a time server, however, does not have to.